Alternating-current generator



Dec. 30, 1930. -r. s. BINDSCHEDLER ET AL 1,786,833

ALTERNATING CURRENT GENERATOR Filed April 5, 1928 2 Sheets-Sheet 1 I N I 'EN TORS.

A TTOR Ei I Dec. 30, 1930'. T. s. BIINIIVJSCHEDLE'R ET AL 1,786,888

' ALTERNATING CURRENT GENERATOR Filed April 5, 192 8 2 Sheets-Sheet 2 6 1: 64 44 IIIGII I INVENTOR. M

I 4 By ATTO NEY.

10 Another object-is means which such Patented Dec-[30, 1930 j P ED T TES THEODORE s; BINDSCHEDLER Ann WILLIAMA. woon, or DETROIT, MIcmGAmns SIGNORS T THESTEEL PENETR-OMETER COMPANY, or minor-r, MICHIGAN, A'coR- M "ALTEnNArme-cUn-REnT GENERATOR i A pp'lication filed April 5,

M The present inventionrelates to means for generating alternating electric currents and specifically to means capable out generating alternating current of any frequency between very wide limits; i 4 7.

Among the objects of the invention is generating means which permits-the variation of the frequency overawvide range while Varying the Voltage by any amount desired.

a Wide range of frequencies maybe obtained without at the same time developing mechanical difficulties. 1

Still other objects will readily occur to those skilled in the art upon referenceto the following a description and accompanying drawings-in which:-

Fig.1 is a plan view of' the generating use therewith Fig. Qis a section the alternator; a a a r Fig. 3 is a schematicdiagram-of a device i dying the invention; 1 7

Fig. 4 is a part elevation of the field mag- 7 net and the motor of the alternator; i Fig. 5 is an elevation ofthe other side of the rotory-and means and the essentials of an instrument for through the windings of Fig. 6 is an elevation of the field magnet for the rotor of Fig. 5. I In application Serial Number 95,597 filed "on March 18, 1926,' on magnetic balances by the present inventors is described an instrument for determining the hardness andthe depth thereof of steels and the like based on the fact that alternating magnetic flux of depth that bears a definite relationto the frequency of the alternationsiand also based on the fact that the hardness is indicated'by the resistance of the metal to the passage of such flux.

The instrument indicatedin the lower right hand corner of Figure 1 is the same in all respects as the one described in the said priorapplication except that the H-shaped magnetv 1928. Serial No. 267574.

test piece and whose upper poles are formed with curved faces 13 concentric with a curved lowerpoles 12 are adapted to contact with a and tapered armature 14 rotatably mounted on a frame 15 and carryingian indicator hand.

A suitable ero end of the scale. i p

This part of the instrument indicateshardness by indicating the proportion of the magnetic flux that passes between the upper V poles 13 of the magnet.

The same instrument is provided with a depth gauge which consists of avoltmeter'; with its scale graduated to indicate depth 7 1 of penetration. i c

' Current for actuating these portions of the instrument is generated by the means shown in the upper part of Figure 1- and 111;; Figures 2 to 6. a

This generating means consists, fi-I'Sl'1,'0f a constant speed motor operating from power lines 31 and driving-a direct current genera-tor32 preferably on a continuation of the motor shaft.

This generator supplies exciting current of alternator 40.

"The alternator 4:0, to be described more in detail later, is mounted ona suitable base and. i aligned with a universal motor 33, receiving its operating current from line wires 34 in one 'of which is a controlling rl eostat 35, which motor drives direct'lyfltlie alternator 40,preferably through having their rotors,

I mounted on the same'shaft. constant value penetrates'such metals to Motor-33 also has directlycon iiected thereto in driving relation a-direct current'genen ator 36 it beingpreferredto use a single shaft 137 for the rotors of all three of these devices, the alternator 40, motor 33, and gen- 'erator 36. The output of generator 36 also goes mainly to a coil in alternator 40, a

a constant voltage to the small portion being shunted through; the

gauge 20. r s I The alternator 40 is shown more in' detail in Figures 2 to 6. In these figures'a housing 141 is shown to contain'two field polerings 42 "and 43 spaced apart by anexc'iting coil e4. 10 whose crossbar carries a coil 11 and whose iOfatliese' two rings, one.,vf.or examplet'42, is

provided with a relatively large number of pole-pieces and the other 43 with only a few. Each is also provided with the usual wind in terminating in the leads 42a and 43a respectively. v

The rotor for alternator 40 comprises two toothed members 45 and 46, each preferably consisting of a number of laminations secured together, monntedon the shaft 47. The member l5 is provided'with as many teeth 48 as there are pole-pieces in the ring while the member 46 has only two teeth These two members 45 and 46 are so located as to rotate within the rings 42 and 43 respectively.

Reference to Figure 2 will show the presence of a second coil 50 within the coil 44. This coil 50 is a coil whose magnetic field is in opposition to the field produced by coil l and is energized by current from generator 36, so that as the speed of rotation of the shaft 47 increases, the current through coil 50 is increased.

WVith the arrangement of gei'ierators and motors shown, a constant excitation current is led to the coil 4stfor alternator l0, w iile the coil 50 is supplied with a current that increases and diminishes with the speed of the two generators 40 and 3G. means, there fore, of suitably proportioned vindings on coils L4: and 50 the exciting iux and consequently the voltage of alternator 40 may be regulated to vary in predetermined ratio to frequency used.

The leads 42a and i354 lead to the contacts 60 and 61 respectively, at the ends of a double pole double throw switch 62 which is connected through its blades to the H magnet 10 of the indicator, so that it is possible to use in said indicator the output from either side of alternator l0 and at the some time open the circuit through the other side.

The generator system, therefore, through its two parts will supply a current permitting a double range of frequencies, one side generating through a range extending from rather low figure to a moderately high figure, while the other side extends from a moderately-high figure to a very high one. For example, from the one side, frequencies of from a hundred or less up to say six or eight hundred are obtained according to the speed of motor 33, while from the other the range will be from a few hundred up to several thousands.

Now having described the invention and the preferred form of embodiment thereof it is to be understood that the said invention is to be limited not to the specific details herein set forth but only by the scope of the claims which follow.

We claim 1. Means for generating an alternating current variable in frequency, with voltage varying at a predetermined ratio, said means consisting of an alternating current generator, an exciting coil therefor, means for supplying to said coil a constant excitation current, means for varying the speed of said generator, and means for varying the effect of the excitation current inversely to the variation in speed of said generator.

2. Means for generating an alternating current variable in frequency, with voltage varying at a predetermined ratio, said means consisting of an alternating current generator, an exciting coil therefor, means for supplying to said coil a constant excitation current, means for varying the speed of said generator, a direct current generator mechanically connected to said alternating current generator whereby its speed is the same, and a second exciting coil supplied with excitation current from said direct current generator and located in close proximity to the first coil, the directions of flux in said coils being opposite.

3. Means for generating an alternating current variable in frequency, with voltage varying at a predetermined ratio, said means consisting of an alternating current generator, an exciting coil therefor, means for supplying to said coil a constant excitation current, means for varying the speed of said generator, a direct current generator mechanically connected to said alternating current generator whereby its speed is the same and a second exciting coil supplied with excitation current from said direct current generator and located within the first coil, the directions of flux in said coils being opposite. 4. An alternating current generator capable of generating a current variable in frequency within wide limits, :with voltage vary ing at a predetermined ratio, comprising a stator having a plurality of separate multipolar fields, a rotor having a like number of armature members each having a-number of teeth corresponding to the number of poles in its respective field, a common excitation coil for said fields, means for supplying to said coil a constant excitation current, a second coil for opposing said excitation, means for supplying to said second coil a current variable directly with the speed of rotation of said rotor, and means for completing an electric circuit through a selected one of said fields.

THEODORE S. BINDSCHEDLER. WILLIAM A. WOOD. 

